Add initial GLImage tracing + stubs

content/common/generic_shared_memory_id_generator.cc

Index: content/common/generic_shared_memory_id_generator.cc
diff --git a/content/common/generic_shared_memory_id_generator.cc b/content/common/generic_shared_memory_id_generator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4211b6e72fe73a8532baaff034592deb350365f8
--- /dev/null
+++ b/content/common/generic_shared_memory_id_generator.cc
@@ -0,0 +1,22 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/generic_shared_memory_id_generator.h"
+
+#include "base/atomic_sequence_num.h"
+
+namespace content {
+
+namespace {
+
+// Global atomic to generate gpu memory buffer unique IDs.
+base::StaticAtomicSequenceNumber g_next_generic_shared_memory_id;
+
+}  // namespace
+
+base::trace_event::GenericSharedMemoryId GetNextGenericSharedMemoryId() {
+  return g_next_generic_shared_memory_id.GetNext();
+}
+
+}  // namespace content